In K240, it's possible for the empire's ore transporter to show up during a firefight. It's even possible for it to be hit with a static inducer.
Can it be destroyed?
It's interesting it can get hit like that. I really doubt it can be destroyed, and destroying it would serve absolutely no purpose.
What you could do is wait until it shows up and ram your asteroid into another asteroid. It's been a while since I played, so I can't remember if capital ships survive asteroid explosions, but I suspect it would simply disappear and come back again later. You could also try building millions of nukes and nuking the crap out of the asteroid, as I think nukes damage ships in orbit.